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MG Midget and Sprite Technical - '79 1500 Poor Acceleration

Hi Guys

I'm hoping for some wise words on the following problem.

The old girl has recently been into a "mg specialist" for a tune up to be able to pass her emmissions part of the MOT. All seemed well for a little while especially at low revs but she refuses to accelerate higher up the rev range (say 3000 rpm onwards). I can hear a loud whoosh as the K&N filters suck in masses of air when I press the fun pedal, but she is extremely hesitant and is unable to turn that demand into extra speed.

I suspect that it has something to do with the mixture setting and the so called "MG Specialist" just weakening the mixture to get it to pass the MOT without really doing a proper tune up that I paid them vast amounts of money to do.

Any help would be greatly appreciated.

D Williamson

whip a plug out, see what colour it is, for a start.

But actually, it needs to go back to the 'Specialist' so that can fix it, if it was expensive.
Rob Armstrong

hi i had exactly that on my bgt. i was advised on here that when k n filters were fitted on car you needed to also put richer needles in carbs. done that and car run superb. i am sure someone will come along on here and confirm that but that is what i would do.check the needles to see if they are standard.
hope this helps bob.

What emmission test for the year it was manufactured?
If its not throwing out smoke what was the definition of emmission test fail for this MOT?
As I understand it the MOT standard is for the year of manufacture not this year.
1) I can't remember any test equipment in the 70's
2) In the 70's I only remember smoke being an indicator of not being legal to drive.
My deisel day car emmits more solids than my midget.

Any comments on my comments are very welcome, Midget going to MOT soon after 10 years off the road so very interested in comments.

Dave Squire - Notts

just looked on mot site and cars up to 1st august 1975 is a visual test and cars after 1st august 1975 will be a metered test.

Hey Trebor,
This matches with your info.
Just had reply to my enquiry at the MOT station I use. The test for a 78 midget is simply on petrol ppm emmitted from the exhaust and visual smoke.
The guys say that with a 1500 triumph unit with standard carbs and needles with normal set up it will fly through so long as:
Its hot.
No choke applying at all.
(All our day motors go there, they only MOT and one of them has a 1500 Herald so should be good advice)
They emphasised the choke settings as the most important thing to be off under normal running (thats not just pushed in, thats not pulling the needles down at all when its pushed in)

Take it back Dave.
Dave Squire - Notts

Thank you all for your comments, much appreciated, I think I'll take a look at the spark plugs first, it should be clear from the condition if the mixture is lean. Then I'll check the choke position to make sure that this is completely off at the carb cold start linkage when the choke control is fully pushed home inside the car.

Depending on what I find, I think it will be a phone call and a trip back to the "Specialist"

Anyone have any idea which needles I might need for use with K&N's?, I think that this needs to be sorted as a matter of course anyway.


D Williamson

This thread was discussed between 11/09/2012 and 12/09/2012

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